The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest apparatus that can be created using a fabrication process) has decreased.
To achieve the shrinking geometry sizes, advanced lithography processes have been developed. For example, the use of extreme ultraviolet (EUV) lithography has been proposed to achieve small geometry sizes. Due to heavy absorption of EUV radiation by substances, an EUV lithography system typically uses a reflective optics apparatus to carry out the lithography processes. However, conventional EUV lithography systems may suffer from a shadow effect, which may lead to device pattern uniformity issues or otherwise degrade lithography performance.
Therefore, while existing EUV lithography apparatuses and processes have been generally adequate for their intended purposes, they are not entirely satisfactory in every aspect.